Cut-off valve for engines.



No. 893,188. 'IIPATENTEDJULY 14, 1908.

- 1. 'B. McBLRoY GUT-OFF .VALVE FOR ENGINES.

I APPLICATION FILED APR.24, 1906- 2 SHEETS-SHEET 1.

I J awuzutoz No. 893,188. a PATENTED JULY 14, 1908 I. B. McELROY.

CUT-OFF VALVE FOR ENGINES.

APPLICATION FILED APR.24, 1906.

z SHEETS-SHEET 2.

UNITED sTATns PATENT OFFICE.

ISAAC ERWIN MCELROY, OF MUSOATINE, IOWA.

CUT-OFF VALVE FDR' ENGINES.

Specification of Letters Patent.

Patented July 14, 1908.

Application filed April 24, 1906. Serial No. 313,455.

The chief objects of this invention are:

first, to simplify and improve the construc tion and increase theefliciency of operation of rotary steam-valves and governing mech anism;second, to obtain by practicable means automatic control of theinduction of steam or other propelling fluid, varyin the cut-offaccording to the load, without owever varying the counter-pressure-aresult hitherto attained, it is thought, only in a Corliss engine alsoto secure sensitiveness in operation of the governor and cut-ofl,without impairing the accuracy or positiveness of action; third, toprovide large full ports, sudden in opening and closing, therebyavoiding wire-drawing and condensation of steam by strangulation; and,further, to maintain a full open exhaust during the whole of the reversestroke of the piston, excepting as may be necessary for cushioning.

One appropriate embodiment of the invention, applied to an ordinaryreciprocatory steam-en me, is illustrated in the accompanying rawin s,which form a part of this specification. t is understood however thatthe invention is independent of the specific construction or style ofengine with which it is incorporated, being adapted for generalapplication, as well as susceptible of embodi ment in different forms,and of modifications in details of structure and arrangement of parts.Without restriction therefore to the particular constructionillustrated, the invention will hereinafter be first fully describedwith reference to said drawings, and then more particularly pointed outin the appended claims. a p

In said drawings, Figure '1 is an enlarged horizontal section throughthe cylinder or piston-chamber and the valve-case, showing the pistonand valve in elevation, also showing a cut-off governor in section. Fig.2 is a horizontal section through the valve, valvecase, and contiguousportion of the cylinder. Fig. 3 is a vertical cross-section on line IIIIII of Figs. 1 and 2. Fig. 4 is a cross-section on line IVIV of Figs. 1and 2. Fig. 5 is a perspective view of the rotary valve. Fig. 6 1s aface view of the cut-01f governor.

The cylinder A, working-piston B, and

piston-rod C are shown as usual in recipro-1 cating en ines.

The va ve-case 1 is shown in a preferred relation, that is arrangedlongitudinally of and beside the cylinder A. Motive fluid,

steam, compressed air or the like, is supplied through the feed-pipe 2shown in Fig. 4, which enters an intermediate part of the valve-case.Exhaust fluid is taken from opposite ends of the valve-case through thedischarge pipes 3. from the cylindrical va ve-seat to opposite ends ofthe piston-chamber.

The illustrated valve, being designed to distribute and control thesteam or other motive fluid for both sides of the piston-chambenistherefore a double or two-part valve. It is shown comprising twovalve-heads, 6 and 7, alined and connected together, either integrallyconstructed as shown, or both splined upon the same valve-rod, orotherwise rigidly united. Said valve-heads rotate in cooperativerelation to the steam-ports 4 and 5 respectively. They. are in the formof hollow cylinders, so constructed and internally divided bylongitudinal partitions 8 as to.

provide in each valve-head an inlet-chamber 9 and exhaust-chamber 10. Itis understood of course that the inlet and exhaust chambers at one sideare inversely arranged with respect to those at the other side, sincesteam is admitted to one end of the cylinder or piston-chamber whileexhausting from the other end. The annular space 11 between thevalve-heads constitutes a medial supply chamber, which is in constantcommunication with the feed-pipe 2. Said chamber 11 is also in opencommunication with the respective inlet-chambers 9, through ports oropenings 12 in the inner ends or end walls of the valve-heads. Theexhaust-chambers 10 are of course closed to said medial supplychamber11, but are in open communication through ports or openings 13 withexhaustchambers 14 in the outer ends of the valvecase, the latter beingin communication with discharge pipes 3. Thus the double valve, as awhole, is in the general form of a hollow partitioned cylinder havingfive chambers, viz: the medial supply 11 and the opposite inlet-chambers9 and exhaust-chambers 10.

Steamorts 4 and 5 extend;

' able relation thereto. preferably freely or loosely mounted on said.

The outer wall or shell of each valve-head is provided with aninlet-port 15 and exhaustport 16, open from the inlet-chamber 9 andexhaust-chamber 10 respectively, and adapt ed to register in alternationwith the particular steam-port 4 or 5 in the valve-seat with which theparticular valve-head is associated. These inlet and exhaust ports 14and 15 are cut or formed longitudinally in the shell of the valve, andare made large or wide to maintain continuous registration with thesteam-ports 4 and 5 during admission and exhaust phases of rotation ofeach valve-head. The valve-shaft being geared to rotate once per eachrotation of the crankshaft, the registering steam-ports are sudden inopening and closing, thereby avoiding wire-drawing and condensation ofsteam by strangulation. The exhaust-ports 16 are especially made wideenough to maintain a continuous full open exhaust during the reversestroke of the piston, except as may be desired at the completion of thestroke for cushioning. In the constructionillustrated, the outer shellsof the valve-heads, in which the ports are formed, consist of turnedsleeves fitted tightly on the circular end walls of the respectivevalve-heads and revolubly fitted within the valve-chamber.

The inlet or live-steam side of each valvehead is provided with anautomatic variable cut-off device, revolving with the valve, andconnected with a governor operated by the speed of the engine to controlthe induction of steam in such manner as to secure uniformity of speed.In the form shown, the said riding or revolving cut-off is an internalsegmental plate 17, movably or slidablyfitted under the shell of thevalve-head at the cutoff or rearward side of the inlet-port 15 thereof,and carrying at its front or advancing ed e a flange or lip 18, thelatter being movabIy arranged in the said inlet-port or between the endsof said port and having an outer convex surface co-cylindrical with thesurface of the valve-head. Hence the passing of the flange or lip 18over the steam-port 4 or 5 in the valve-seat determines the period ofcut-off, or terminates the induction of propelling fluid, allowing thepropelling fluid thereafter to act expansively. Said cut-off device 17is carried by a radially arran ed spider or support 19, co-axial andrevolu le with the valve-head, but capable of a vari- The cut-off deviceis spider or support 19, as by pin and slot fastenings 20, or by othersuitable means, whereby the riding cut-off is always properly seated bypressure of steam on the inner or end face of the segmental plate 17.

As'shown, the spiders or supports 19 for the two cut-offs are keyed orfixed on a shaft 21, which is revolubly arranged in the center ofthevalve,within ahollowvalve-shaft 22, the

latter being keyed or fixed to the valve. The said cut-off shaft 21passes out through said valve-shaft 22 beyond one end of the valvecase.The valve-shaft 22 may be either an independent hollow shaft, as shown,or it may be an extension of the valve-rod proper 23, which is shownextending out through the opposite end of the valve-case. The cutoff maybe controlled by any suitable device, as by means of a speed-governor orother mechanism operating on the cut-off shaft 21 For example, in thecase of a locomotive engine, a lever may be employed to control thevariable cut-off. However, as a part of my invention, I have devised theconstruction now to be described, in which is employed a speed-governorrevoluble with the valve and operatively connected with the cut-oilshaft.

On the end of said hollow valve-shaft 22- is a,

centrifugal governor 24, of any suitable type or construction, which isconnected with the cut-off shaft 21 in such manner as to rotate thesame, with the valve-sh aft, but at a variable relation thereto,according to the speed of the engine. Hence any variation in speedcauses a variable relative position of the shafts 21 and 22, therebymoving the riding cut-oif device, so as to lengthen or shorten theperiod of admission. The illustrated governor comprises a disk orelement mounled on the valveshaft 22, and carrying springconnectedweighted levers 25, which are connected by links 26 with a yoke orcross-piece 27 to the cut-off shaft 21, thereby making a yieldingconnection between the shafts adapted to turn them together but allowinga variation in their relative positions under the centrifugal action ofthe weights. The governor being thus directly and closely connected withthe cut-off, has its sensitiveness greatly increased without impairingits positive action. It will be noted, moreover, that the variations inthe periods of admission, due to the action of the governor and ridingcut-off, does not affect the counterpressure, since the cut-oif isvaried by a restriction of the width of the inlet-ports 15, withouthowever varying the position of the valve itself, nor varying theposition or the size of the exhaust-ports 16, which latter maintain afull open exhaust for the reverse stroke of each side of the piston.

The valve may of course operate two or more cylinders as well as onecylinder, in which instance the valve-case would be arranged between thecylinders, steam-ports being provided for the respective cylinders, eachfor. successive registration with the inlet and exhaust ports of thevalve.

Having thus fully described my invention, what I claim as new and desireto secure-by Letters Patent of the United States is 1. In rotary valvemechanism, the combination of a cylindrical valve-case having a ing ahollow cylindrical head having lateral admission and exhaust portsadapted to register with the port in said valve-case, and a variableriding cut-off carried inside said nal riding cut-off mounted on saidshaft comprising a loosely held segmental plate fitted under the cut-offside of the admission port and having a flange or lip fitted within saidadmission port against'the interior of the valve-case, said cut-offbeing seated by steam pressure.

3. In rotary valve mechanism, the combination of a cylindricalvalve-chamber having a port therein, a hollow rotary valve fitted insaid chamber and having a cooperative inletport, a variable cut-offdevice revoluble with the valve and movably arranged in the inletportthereof, said cut-off device having an outer surface flush with theinterior walls of the valve chamber and being freely or loosely held,and seated by pressure of motive-fluid in the valve.

4. A rotary valve comprising a hollow cylindrical shell having a lateralinlet-port, an independently-turnable rod or shaft axially arrangedtherein, a radially-arranged spider or support on said rod, and a ridingcut-off device carried by said spider, said device comprising asegmental plate fitted under the inner wall of the valve-shell at thecut-off side of its port and being loosely fastened on said spider.

In testimony whereof I affiX my signature, in presence of two witnesses.

ISAAC ERWIN MQELROY.

Witnesses:

G. ALLBEE, C. W. BENSHOOF.

